So I had a look around to see what else there was, and was quite pleased there are some very cool and very powerful tools out there that are open source and available.
Unfortunately there is little perl integration with both commercial (like inktomi which has a Python but not perl API) and open source search engines.
There is an alpha / experimental interface to an out-of-date version of swish on CPAN but thats all that is obvious.
some interesting sites are
I think I'll have a closer look at the last two to either inspire or integrate heron with them.